The present invention relates to the field of suspension thrust bearings used, in particular, on motor vehicles in the telescopic suspension struts for the steered wheels.
A suspension thrust bearing generally comprises an upper ring and a lower ring, between which rolling bodies, in the form of balls or rollers, are arranged.
The invention relates more specifically to the suspension thrust bearings which comprise at least one cap made of synthetic material in contact with one of the two rings of the bearing.
In a way known per se, the suspension thrust bearing is arranged in the upper part of the suspension strut between a lower plate, generally made of metal, also acting as a seat for a suspension spring, and an upper element secured to the body of the vehicle. The spring of the suspension device is installed around the rod of the shock absorber piston, the end of which is secured to an elastic mount. The suspension thrust rolling bearing allows a rotational movement between the spring plate, which can move in rotation, and the elastic mount which is fixed to the body of the vehicle. The suspension thrust bearing also makes it possible to transmit axial forces between the spring and the body of the vehicle. The relative angular movement of the spring plate and of the elastic mount results from a turning of the steered wheel and/or compression of the suspension spring. Reference may be made to French document No. 2 779 096.
The suspension thrust rolling bearings are situated under the body of the vehicle and in close proximity to the wheels which, particularly in rainy weather, throw up contaminants likely to enter the bearing.
In a way known per se, as in documents U.S. Pat. No. 4,995,737 or EP-A-390 331, use may be made of a device employing one or two plastic caps, each cap capping a ring and having means of axial retention collaborating with the other cap. The caps are generally made of glass-fibre-reinforced plastic to give them the necessary strength and rigidity. This material proves to be too rigid and too abrasive for a rubbing seal formed of this material, in the form of a lip for example, to be effective enough.
The invention proposes a suspension thrust rolling bearing with effective sealing capable also of being secured to the lower plate prior to mounting on the strut so as, with the said plate, to constitute a compact assembly which can easily be handled and transported without the risk of accidental loss of one of the components.
The suspension thrust rolling bearing device according to one aspect of the invention is of the type comprising a first ring secured to a cap, a second ring made of thin sheet, a row of rolling bodies arranged between the two rings, a cap secured to the first ring and a plate capable of forming a seat for a spring. The plate comprises a means for securing it directly axially to the second ring, the said means being capable of collaborating with retaining means arranged on a tubular portion of the second ring.
Advantageously, the second ring comprises a first toric portion tailored to the rolling bodies, and a second toric portion extending from the first toric portion radially inwards and axially away from the rolling bodies.
In one embodiment of the invention, the second ring comprises a radial portion extending radially inwards from the toric portion and a tubular portion extending axially away from the rolling bodies.
In one embodiment of the invention, the second ring comprises a retaining portion extending from the second toric portion.
In one embodiment of the invention, the retaining portion extends radially inwards.
In one embodiment of the invention, the retaining portion extends radially outwards.
Advantageously, the plate comprises an annular groove formed from a surface in contact with the second ring.
In one embodiment of the invention, the groove has two concentric surfaces, one of them more or less cylindrical and the other having at least one radial enlargement situated away from the bottom of the said groove and capable of collaborating with the second ring.
In one embodiment of the invention, the groove has a diameter smaller than that of the imaginary circle that passes through the centre of the rolling bodies.
Advantageously, the second ring is capable of collaborating with the groove.
As a preference, the plate has a metal insert and a part made of synthetic material, for example moulded.
The plate may comprise at least one radial projection arranged in a depression or slot in the second ring.
The plate may also be press-fitted onto the second ring.
The plate may comprise a radial bulge capable of collaborating with a radial bulge of the cap to secure these elements together axially.
A suspension thrust rolling bearing is thus produced, whose size both axial and radial is not altered by comparison with known rolling bearings and which has excellent sealing and excellent means of retaining these various elements on one another.